The Nervous System Flashcards
What is stimulus?
Any change in your environment
Ex: light, sound, etc
What is the Central Nervous System?
The nerves connected to your brain and spinal chord
What is the peripheral nervous system?
The nerves that branch from the CNS to all parts of the body
What is an impulse?
An electrical message that Is carried along a neuron
What is the role of the sensory neuron
Carries a message from a sense organ to the CNS
What is the role of the motor neuron
Takes a message from the CNS to a muscle or gland
What is the role of the inter neuron
Connects sensory and motor neurons and carries messages within the CNS
What is the role of the cell body
Produce neurotransmitters
What is the role of dendrites
Fibres that receive information and carry it towards the cell
What is the role of the axon
Conducts impulses away from the cell body
What is the role of the schwann cell
Wrap their fatty cell membranes around axon, produce myelin sheath
What is the role of the myelin sheath
- Insulates neuron
- Speeds up transmission
What is the role of the nerve endings
Connects sensory neurons to receptor cells or sense cells
What is the role of the neurotransmitter swellings
Release chemicals that carry impulses from one nerve cell to another
What is a ganglion?
A group of cell bodies located outside the CNS
What is the transmission of nerve impulse?
The movement of electrical impulse along a neuron involving the movement of ions in and out of neurons
What is a resting neuron?
A neuron that is not carrying an impulse
Define threshold
The minimum stimulus needed to cause an impulse
What is the all or nothing law?
A law that states that if the threshold is not reached, no impulse is carried
What is the refactory period?
Short span of time after a neuron has carried an impulse during which stimulus fails to cause a response
This is necessary to allow the impulse to pass from one neuron to another
What is a synapse?
Region where two neurons come into close contact
What is the synaptic clef?
The gap between two neurons, bridged by neurotransmitters
What is a neurotransmitter
Chemical released across a synaptic clef to carry a signal from one neuron to another
Give a summary of the passage of impulse across a synapse
- Electrical impulse arrives at axon terminal
- This stimulates neurotransmitter swellings in the pre-synaptic neuron to diffuse neurotransmitters across the synaptic clef
- Neurotransmitters combine with receptors on post synaptic neuron and are broken down by enzymes and impulse starts in next neuron
- Digested Neurotransmitters reabsorbed back into the swellings which allows them to be recycled and reused upon the arrival of new impulse
What factors does the speed of impulse depend on?
- Presense of myelin
- Diameter of dendrite or axon. Larger = faster
What are the most common examples of neurotransmitters?
- Dopamine
- Noradrenaline
- Acetylcholine
Name a disorder that affects the nervous system, a cause, symptoms, preventative measures and treatment for it
Name: Parkinsons
Cause: brain reduces the normal amount of dopamine it makes
Symptoms: 1. Trembling hands/legs. 2. Stiff and rigid muscles. 3. Difficulty walking
Prevent: No way to prevent
Treatment: Physiotherapy
What is the role of the cerebrospinal fluid
- Shockabsorber
- Exchange medium between blood and brain
What is the role of the cerebrum
- Control voluntary movements
- Receiving and interpreting impulses from the sense organs
- Thinking, intelligence, personality, memory, language
What is the role of the cerebellum
- Controls muscle coordination and balance
- Responses are involuntary
What is the role of the modula oblongata
Controlls involuntary actions such as breathing, swallowing, blood pressure, coughing
What is the role of the thalamus
Sorting centre, sends all incoming impulses to the correct part of the brain
What is the role of the hypothalamus
Regulates constant internal environment (homeostasis)
What is the spinal chord protected by
The meningees (3 membranes) and cerebrospinal fluid
What is the role of the spinal chord
Transmits impulses to and from the brain and controls reflex actions
Why is grey matter called so?
Contains cell bodies and dendrites with few axons
Why is white matter called so?
Contains many axons and much myelin
What is reflex action?
Involuntary response to a stimulus
Eg: coughing, blinking
What is the process of reflex action
- Stimulus is detected by pain in the skin
- A message is carried by the sensory neuron in the spinal chord
- The message is passed on to the interneuron and then to a motor neuron and so into the muscles
- The muscles respond by contracting and pulling your hand from the stimulus
